Thiocyanic and dithiocarbamic anhydrides and the process of making the same



Patented Eco. 13, 1938 umreb S'EA'IES PATENT OFFICE THIOCYANIG AND DITHIOCARBABHG AN- HYDRIDES AND THE PROCESS OF MAKING THE SAME Jean Claudia, Paris, France, asslgnor to Socit Anonyme des Matieres Colorantes & Produits Chimlques de Saint-Denis, Paris, France, a

company of France No Drawing. Application July 2c, 1935, Serial No. 33,389. In France August 1, 1934 is Claims. 7 (01. 260-445) I This invention relates to new compounds con-.

slsting in thiocyanic anhydrides, and to the manufacture of the same.

' It is an object of'thls invention to produce thiocyanic anhydrides which are especially reactive and in this respect are suitable for synthesis of vulcanization accelerators, an'ti-cryptogamic products, dyestuffs and so on.

By causing cyanogen chloride to act on a solu- 10 tion of sodium dimethyl-dithiocarbamate at temperatures between 20 and 70 0. there is obtained in good yield and in good purity sodium tetramethylthiuram-monosulphide with the formation of sulphocyanide. The reaction proceeds in accordance with the following scheme:

\GHI If the temperature at which the cyanogen chloride is introduced is reduced to about 0 C. there v is no longer observed the formation of yellow crystals of the sodium thiuram' mono-sulphide 0 but white flakes are precipitated; the formation of sulpho'cyanide cannot be detected and the white product, after having been filtered andwashed at about 0 0., constitutes a product which is unstable at ordinary temperature. It

has a disagreeable odour and becomes yellow and tarry.

This substance is presumed to constitute an intermediate product in the reaction above referred to and, in fact, if it is mixed with a solu- 40 tion of dimethyl-dithiocarbamate the thiurammonosulphide is obtained, after a short time, at ordinary temperature. The course of the reaction, is thus as follows With the aid of the intermediate product (I) it is thus possible to prepare monosulphides of unsymmetrical thiurams, for example, according to the scheme:

(cm),Nc=s+ c.m):N-o=soH:),N-c=s CN Na (smear-t e The possibilities in; the synthesis of mixed products are illustrated in the table which is given hereinaften,

Intermediate products corresponding with the intermediate product (1) can be obtained from all dithiocarbamates of the formula:

in which R and B may be of any nature, whether aliphatic or aromatic. In this case the intermediate product may be considered as a mixed anhydride of the dithiocarbamic acid and cyanic or thiocyanic acid. The tendency to undergo alteration and the reactivity of these anhydrides of cyanic orthiocyanic acid vary according to the nature of the dithiocarbamate. when R and R. represent the methyl group the cyanic anhydride is very much less stable than in the cases in which R and R represent groups of higher molecular weight. The anhydrides of the formula:

0.11 SON and Ca s N-O:B Oe a SON are stable at ordinary temperature for several 1st reaction:

By means of the cyanic or thiocyanic anhydride, which is isolated at a low temperature, it is possible to obtain, by condensation with any xanthates, a large number of mixed monosul- 'phides.

It has also been found that theseanhydrides derived from dithiocarbonic acids are capable of reacting not only with derivatives of dithiocarbonates but also with all compoundscontaining a labile hydrogen atom, sulphocyanic acid being .eliminated. The possibilities of synthesis with the aid of these cyanic anhydrides are extraordinarily great and can only be compared with those of the diazo compounds with which it is possible to realize very numerous combinations. Just as it has become possible to synthesize an unlimited number of azodyestuifs thanks to the reactivity of the diazo group, so also is it possible to carry out a very large number of new syntheses, by means of the cyanic or thiocyanic anhydrides, according to the general scheme:

I AN H=labile hydrogen in which R and R may be of most diverse natures. In the table which is given hereinafter there will be found some instances of the condensation of the'cyanic anhydrides with dithiocarbonates and their derivatives, with mercaptans, with amines and with phenols. The variety of the syntheses permits the production of com pounds of commercial importance, in some cases as vulcanization accelerators, in other cases as anticryptogamic products, as dyestuffs and so on.

The reactivity and even the existence of these cyanic and thiocyanic anhydrides has hitherto escaped notice. This is indeed not due to lack of published researches on cyanogen chloride. Many condensation products have been obtained withthe aid of cyanogen bromide or cyanogen chloride, although I. Traube (B. vol. 18, page 461) has gone so far as to comment on the small reactivity of cyanogen chloride after having attempted unsuccessfully to condense it with hydroxylamine, urea, iodoform and so on. The same author has described the action of cyanogen chloride on meta-aminobenzoic acid (B.v vol. 15, page 2113), which yielded meta-cyanamidobenzoic acid with which he was able to carry out the synthesis of guanidine according to the scheme previously applied by Hoflmann to ani- I. von Braun and line (A. vol. 67, page 129). A. Trumpler have subjected pentamethylenesulphide to the action of cyanogen bromide (B.

In this case the,an-.

vol. 43, page 550). But they were unable to identify the product of the reaction to which, on hypothetical grounds they attributed the following formula:

soN

Br They also succeeded in preparing from dibromopentane and potassium sulphocyanide, an ester. pentamethylene-sulphocyanide, to which they attributed the formula: NCS(CH2) 5SCN, but they make no mention of a reactivity approach ing that of the anhydrides of the present invention. On the contrary they report on the stability of the product as comparable with that of the diand tri-methylene sulphocyanides. I. von Braun has investigated the reaction of cyclic bases with cyanogen bromide (B. vol. 40, page 3914, vol. 42, page 2035, vol: 43, pages 550, 1353, 2879, and 3209).

Various authors have investigated the action of cyanogen chloride and cyanogen bromide on organo-magnesium compounds. Karrer has studied their action on hydrocarbons and phenol ethers (Helv. vol. 2, page 482 and vol. 3, page 261). I

I. von Braun and Paul Engelbertz have studied the decomposition of mixed organic sulphides by the action of cyanogen bromide and have obtained compounds of the typeR-SCN (B. vol. 56, page 1573), but these authors make no mention of any capacity for condensation such as is possessed by the related derivatives of the type:

' R-C=S v SON i In U. S. patent to Powers No. 1,674,122 mention is made of the formation of mono-sulphides of alkyl' esters of thiocarbonic acids by the action of cyanogen chloride or cyanogen bromide on alkyl xanthates but the possibility of the existence of cyanic or thiocyanic anhydrides, and

'in consequence the considerable reactivity of these bodies, is not suggested. In fact the proportions between the reactants (about 0.5 mol of cyanogen halide and 1 mol of xanthate) do not preclude but on the contrary enhance. the combination of cyanic or thiocyanic anhydride, if formed 8:. an intermediate product, with further xanthate. It has further been found that the group SCN, which is considerably activated in the case of the cyanic anhydrides by the proximity of the group 0:5, is likewise capable of reacting with compounds containing labile hydrogen, although in a much less active manner. In this case the products may be regarded as esters of cyanic or thiocyanic acid. These products, unlike the cyanic anhydrides, are al- 3 ready known although their reactivity has not hitherto been recognized. If, for example, cyanogen chloride is introduced into a solution of sodium mercapto-benzothiazolate in the cold there is obtained a white compound which, when carefully recrystallized from alcohol, melts at 89 C. and has the percentage composition S=31.8 per cent, N=14.8 per cent, C=50.3 per cent, H=2.8 per cent, which agrees with the formula: V

This compound is probably that described in the U. S. Patent to Scott No.i1,838,159. (This compound, having a certain degree of reactivity,

when heated towards C. yields a reddish compound of surprising stability).

This cyanic ester is likewise capable of reacting in certain cases like the cyanic anhydrides. With a xanthate, for example, it reacts in the following manner:

Curiously it reacts with sodium mercaptobenzothiazolate to yield not the monosulphide but the disulphide of benzothiazole, with the formation of sodium cyanide, according to the scheme:

has disappeared. Then the cyanic anhydride is isolated by filtration, decantation or in some other manner.

The reactivity of the cyanic anhydrides is thus extended to the thiocyanic esters according to the following two types of reaction:

The procedure for making the compounds may be as follows:

Cyanogen chloride is introduced into a solution containing a compound of the formula:

(b) Condensation of the cyanic anhydride and ester with a compound containing labile hydrogen The cyanlc or thiocyanic anhydrides and esters can be condensed with all compounds containing a labile hydrogen atom according to the scheme hereinbefore indicated. For this reaction various media may be used. The formation of sulphocyanide and in certain cases (the cyanic esters) of cyanide can easily be followed; then there is formed the new compound RXR (X=NH, O, NH-NH and so on).

When the cyanic anhydride is condensed with a molecule of the same compound as that from which it is derived there is obtained a symmetrical product. among others, the following symmetrical products, some of which have hitherto not been known:

or a salt thereof. The temperature to be ob- Appearanoe gg? Observations S=CSC=S Clear yellow crystals 54-55 0 CH; O OH: I

e=c-s-o=s N .-.-.-do 55 C2H5 CI r S=CSC=B Dark yellow crystals 54-55 I sopropyl-derlvatlve.

I C3111 C1111 S=CSG=S Brown nil Derivative of the commercial mix I tore o! butyl alcohols. C4419 04 S=0SC=S Yellow oil Derivative ol the commercial mixture of amyl alcohols.

CsHu GaHn s=o-s- :=s Yellow crystals.-- 109-110 161B) mom),

' Cream-white crystals 178 N N CSS--C s e CH; cm Yellow crystals in NCS-CN C055 C0 It is thus possible to obtain,

4 2,139,985 by condensing cyanic anhydrides oi the type: or cyanic esters with other compounds containing 3 labile hydrogen, there can be obtained, among K others, the following compounds: 5 \s 5 Appearance gggg Observations 7 1o N o s=c s c Yellowish-white crystals 7 122 s=c-s-o 80 N(C:H|): s

B=CB--G=S Yellow crystals 55 1h" 1% I 20 S=?SC=S n Very unstable.

H l): CH: 25

S=CSC=S D0.

c (6 JJsHa 30 B=(IJSC=S Bright yellow crystals".-. 44 Vogy unstable; lsopropyl derivave. I (Cir): (8:31

8=C-SC=S Yellow oil Derivative 0! commercial bu l alcohol. 35

i (die. to.

s=c'-s-c=s n Derivative oi commerclni isoamyl alcohol.

e=o-o-O Dukredoil v 7 S=Cli-O Yelloworystals' 124 V 4 50- (aim Faintl cream tals.-.- 9B

(oil) No, V o

s=('1-o 0m Grcenlsh crystalsins 136 (one,

ang na-O Clea: yellow noodles 127 B-i-NHOOE; ooxouiu m....--.- w:

' Appearance gg gg Observations cn' s= JNH- oom Yellow crystals 12a N S=(i1 N(CH Straw-coloured crystals---. 79

/N Ha):

s=o-s-o do..-.. 112

CgHa S=CBC\ Cream-whitecrystals 11s OgHgs The foregoing list of products obtainable by the invention is in no way limitative but represents only some products selected at random from hol radical is used to mean the monovalent radi-' cal resulting from the elimination of the hydrogen atom from the hydroxy group characterizing the alcoholic function of an alcohol, (thus for instance, ethanol radical means C2H5O) similarly the expression amine radical. is used to mean the monovalent radical resulting from theelimination of one hydrogen atom from the amino group characterizing an amine (thus, for instance, monomethylamine radical means CH3.NH)

What I claim is:

1. The method which comprises reacting at a temperature of about 0 C. an alkali metal salt of dimethyl dithiocarbamic acid with an amount of a cyanogen halide at least sufflcient to convert the whole amount of saidsalt to cyanic anhydride of the formula so as to avoid further reaction of the latter with free alkali metal-salt of dimethyldithiocarbamic acid, whereby the anhydride isprecipitated as white flakes, and isolating said anhydridefrom the cooled solution.

2. The method which comprises cooling to a temperature of about 0 C. an aqueous solution of sodium dimethyldithiocarbamate, reacting the sam'eat said temperature with a large amount of cyanogen chloride so as to precipitate the,

whole dimethyldithiocarbamate aswhite flakes of a cyanic anhydride of the formula and isolating the flakes from the solution at said temperature. r

3. The method which comprises cooling to a temperature of about 0 C. an aqueous solution of sodium methylphenyldithiocarbamate, reacting the same at said temperature with an amount of cyanogen chloride at least sufficient to convert the whole amount of sodium methylphenyldithiocarbamate to a cyanic anhydride of the formula and isolating the said anhydride from the solution.

4. A cyanic anhydride of the formula cm s on, SCN

being a white product, unstable at ordinary temperature, having a disagreeable odor,

5. A method for the manufacture of cyanic anhydride which comprises reacting at a temperature of about 0 C. a compound of the formula wherein R is a dialkylamino radical and M is a monovalent metal, with at least one equivalent weight of cyanogen halide. I

7. A method for the manufacture of cyanic anhydride which comprises reacting at a temperature of about C. a compound of the formula wherein R is a diaryalmino radical and M is a monovalent metal, with at least one equivalen weight of cyanogen halide.

8. A method for the manufacture of cyanic anhydride which comprises reacting at a temperature of about 0 C. a compound of the formula wherein R is an arylalkylamino radical and M is a monovalent metal, with at least one equivalent weight of cyanogen halide.

9. A method for the manufacture of cyanodithiocarbamic compounds, which comprises reacting at a temperature of about 0 C. a dithiocarbamic compound of the formula MLFM wherein M denotes a monovalent metal and R is an alkyl radical, with an amount of a cyanogen halide at least suflicient to effect substitution of n so S-fGN wherein R is a dialkylamino radical. 12. A compound of the formula wherein R is a diarylaniino radical. 13. A compound of the formula R-O S'CN wherein R is an arylalkylamino radical.

JEAN CLAUDIN. 

